title

date

icon

background

XPath Selectors {.cols-6}

Getting started {.col-span-2}

Xpath test bed (whitebeam.org)

Test in Firefox or Chrome console:

$x('/html/body')
$x('//h1')
$x('//h1')[0].innerText
$x('//a[text()="XPath"]')[0].click()

Descendant selectors {.col-span-2}

Xpath	CSS
`//h1`	h1
`//div//p`	div p
`//ul/li`	ul > li
`//ul/li/a`	ul > li > a
`//div/*`	div > *
`/`	:root
`/html/body`	:root > body
{.show-header}

Order selectors {.col-span-2}

Xpath	CSS
`//ul/li[1]`	ul > li:first-child
`//ul/li[2]`	ul > li:nth-child(2)
`//ul/li[last()]`	ul > li:last-child
`//li[@id="id"][1]`	li#id:first-child
`//a[1]`	a:first-child
`//a[last()]`	a:last-child
{.show-header}

Attribute selectors {.col-span-3 .row-span-2}

Xpath	CSS
`//*[@id="id"]`	#id
`//*[@class="class"]`	.class
`//input[@type="submit"]`	input[type="submit"]
`//a[@id="abc"][@for="xyz"]`	a#abc[for="xyz"]
`//a[@rel]`	a[rel]
`//a[starts-with(@href, '/')]`	a[href^='/']
`//a[ends-with(@href, '.pdf')]`	a[href$='pdf']
`//a[contains(@href, '://')]`	a[href*='`:`//']
`//a[contains(@rel, 'help')]`	a[rel~='help']
{.show-header}

Siblings {.col-span-3}

Xpath	CSS
`//h1/following-sibling::ul`	h1 ~ ul
`//h1/following-sibling::ul[1]`	h1 + ul
`//h1/following-sibling::[@id="id"]`	h1 ~ #id
{.show-header}

jQuery {.col-span-3}

Xpath	CSS
`//ul/li/..`	$('ul > li').parent()
`//li/ancestor-or-self::section`	$('li').closest('section')
`//a/@href`	$('a').attr('href')
`//span/text()`	$('span').text()
{.show-header}

Misc selectors {.col-span-3}

Xpath	CSS
`//h1[not(@id)]`	h1:not([id])
`//button[text()="Submit"]`	Text match
`//button[contains(text(),"Go")]`	Text contains (substring)
`//product[@price > 2.50]`	Arithmetic
`//ul[*]`	Has children
`//ul[li]`	Has children (specific)
`//a[@name or @href]`	Or logic
`//a	//div`
{.show-header}

XPath Expressions {.cols-3}

Steps and axes {.secondary}

-	-	-	-
`//`	`ul`	`/`	`a[@id='link']`
Axis	Step	Axis	Step
{.left-text}

Prefixes

Prefix	Example	Means
`//`	`//hr[@class='edge']`	Anywhere
`/`	`/html/body/div`	Root
`./`	`./div/p`	Relative
{.show-header}

Axes

Axis	Example	Means
`/`	`//ul/li/a`	Child
`//`	`//[@id="list"]//a`	Descendant
{.show-header}

XPath Predicates {.cols-3}

Predicates

//div[true()]
//div[@class="head"]
//div[@class="head"][@id="top"]

Restricts a nodeset only if some condition is true. They can be chained.

Operators

# Comparison
//a[@id = "xyz"]
//a[@id != "xyz"]
//a[@price > 25]

# Logic (and/or)
//div[@id="head" and position()=2]
//div[(x and y) or not(z)]

Using nodes

# Use them inside functions
//ul[count(li) > 2]
//ul[count(li[@class='hide']) > 0]

# Returns `<ul>` that has a `<li>` child
//ul[li]

You can use nodes inside predicates.

Indexing

//a[1]                # first <a>
//a[last()]           # last <a>
//ol/li[2]            # second <li>
//ol/li[position()=2] # same as above
//ol/li[position()>1] #:not(:first-child)

Use [] with a number, or last() or position().

Chaining order

a[1][@href='/']
a[@href='/'][1]

Order is significant, these two are different.

Nesting predicates

//section[.//h1[@id='hi']]

This returns <section> if it has an <h1> descendant with id='hi'.

XPath Functions {.cols-2}

Node functions

name()            # //[starts-with(name(), 'h')]
text()            # //button[text()="Submit"]
                  # //button/text()
lang(str)
namespace-uri()

count()           # //table[count(tr)=1]
position()        # //ol/li[position()=2]

String functions

contains()        # font[contains(@class,"head")]
starts-with()     # font[starts-with(@class,"head")]
ends-with()       # font[ends-with(@class,"head")]

concat(x,y)
substring(str, start, len)
substring-before("01/02", "/")  #=> 01
substring-after("01/02", "/")   #=> 02
translate()
normalize-space()
string-length()

Boolean functions

not(expr)         # button[not(starts-with(text(),"Submit"))]

Type conversion

string()
number()
boolean()

XPath Axes {.cols-2}

Using axes

//ul/li                       # ul > li
//ul/child::li                # ul > li (same)
//ul/following-sibling::li    # ul ~ li
//ul/descendant-or-self::li   # ul li
//ul/ancestor-or-self::li     # $('ul').closest('li')


`//`	`ul`	`/child::`	`li`
Axis	Step	Axis	Step
{.left-text}

Steps of an expression are separated by /, usually used to pick child nodes. That's not always true: you can specify a different "axis" with ::.

Child axis

# both the same
//ul/li/a
//child::ul/child::li/child::a

child:: is the default axis. This makes //a/b/c work.

# both the same
# this works because `child::li` is truthy 
//ul[li]
//ul[child::li]

# both the same
//ul[count(li) > 2]
//ul[count(child::li) > 2]

Descendant-or-self axis

# both the same
//div//h4
//div/descendant-or-self::h4

// is short for the descendant-or-self:: axis.

# both the same
//ul//[last()]
//ul/descendant-or-self::[last()]

Other axes {.row-span-2}

Axis	Abbrev	Notes
`ancestor`
`ancestor-or-self`

| following | | | | following-sibling | | | | preceding | | | | preceding-sibling | | | {.headers}

There are other axes you can use.

Unions

//a | //span

Use | to join two expressions.

XPath More examples {.cols-2}

Examples

//*                 # all elements
count(//*)          # count all elements
(//h1)[1]/text()    # text of the first h1 heading
//li[span]          # find a <li> with an <span> inside it
                    # ...expands to //li[child::span]
//ul/li/..          # use .. to select a parent

Find a parent

//section[h1[@id='section-name']]

Finds a <section> that directly contains h1#section-name

//section[//h1[@id='section-name']]

Finds a <section> that contains h1#section-name. (Same as above, but uses descendant-or-self instead of child)

Closest

./ancestor-or-self::[@class="box"]

Works like jQuery's $().closest('.box').

Attributes

//item[@price > 2*@discount]

Finds <item> and check its attributes

Also see

Devhints (devhints.io)
Xpath test bed (whitebeam.org)

Files

xpath.md

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